This invention relates to valve seals and methods of adjusting valve seals.
Most butterfly valve seals are made of elastomeric materials which are flexible and resilient, and which create an interference engagement with a valve disc to effect a leak-free seal. Generally, the elastomeric seals in small butterfly valves are dimensionally fixed and they allow no adjustment of the amount of interference between the seal and disc. Larger butterfly valves normally offer an ability to adjust this interference so as to overcome the larger tolerance deviations likely in large components. The most common means of adjustment of the seal is achieved through the action of a compression ring. This ring mechanically squeezes the seal increasing the interference between the seal and disc.
Other methods of adjusting the amount of interference between the seal and disc are described in U.S. Pat. Nos. 3,304,050, 3,540,696, 3,544,066 and 3,958,314.